Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster during spontaneous recrudescence after exposure to short photoperiod

Syrian hamsters are photoperiodic rodents in which reproduction, including testicular function, is stimulated by long photoperiod exposure and curtailed by exposure to a short photoperiod. The objectives of this study were to characterize the testis histomorphometrically and to determine the role of the proliferation and apoptosis phenomena in the recovery of the seminiferous epithelium during spontaneous recrudescence after exposure to short photoperiod. The study was performed using conventional light microscopy, proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase (TdT)‐mediated dUTP in situ nick end labelling staining, image analysis software, and transmission electron microscopy in three recrudescence groups: initial recrudescence (IR), advanced recrudescence (AR) and total recrudescence (TR). The results morphometrically pointed to the gradual recovery of the testicular and tubular volumes, as well as of the seminiferous epithelium. Among the IR and AR groups, the increase in testicular and tubular volumes was accompanied by an increase in tubular diameter and length, with an increase in interstitial volume. From AR to TR, there was an increase in the tubular and total volumes, but, in this case, with a gradual increase in tubular diameter. Recovery of the seminiferous epithelium was accompanied by changes in apoptosis and proliferation activities. The first decreased halfway through the process, and the second remained higher than the control levels throughout the recrudescence stage. Alterations in the spermatozoa were ultrastructurally observed, which indicated that spermiogenesis was not yet completely normal. In conclusion, spontaneous testicular recrudescence in Syrian hamster comprises two histomorphometrical phases: the first related to an increase in tubular length and diameter and interstitial volume and the second depending principally on the gradual increase in tubular diameter. The restoration of the seminiferous epithelium is due to apoptosis reaching normal values in the AR group accompanied by higher proliferative activity than that observed in the Control group.     

Endocrine changes in sows exposed to elevated ambient temperature during lactation

Seven sows were placed into one of two environmental chambers at 22 C, 5 d prior to farrowing. On day 9 of lactation, one chamber was changed to 30 C (n = 4) and the other remained at 22 C (n = 3). On days 24 and 25, blood samples were collected every 15 min for 9 hr and 7 hr, respectively. On day 24, thyrotropin releasing hormone (TRH) and gonadotropin releasing hormone (GnRH) were injected iv at hour 8. On day 25 naloxone (NAL) was administered iv at hour 4 followed 2 hr later by iv injection of TRH and GnRH. Milk yield and litter weights were similar but backfat thickness (BF) was greater in 22 C sows (P less than .05) compared to 30 C sows. Luteinizing hormone (LH) pulse frequency was greater (P less than .003) and LH pulse amplitude was less (P less than .03) in 22 C sows. LH concentrations after GnRH were similar on day 24 but on day 25, LH concentrations after GnRH were greater (P less than .05) for 30 C sows. Prolactin (PRL) concentrations were similar on days 24 and 25 for both groups. However, PRL response to TRH was greater (P less than .05) on both days 24 and 25 in 30 C sows. Growth hormone (GH) concentrations, and the GH response to TRH, were greater (P less than .0001) in 30 C sows. Cortisol concentrations, and the response to NAL, were less (P less than .03) in 30 C sows. NAL failed to alter LH secretion but decreased (P less than .05) PRL secretion in both groups of sows. However, GH response to NAL was greater (P less than .05) in 30 C sows. Therefore, sows exposed to elevated ambient temperature during lactation exhibited altered endocrine function.     

Effects of short photoperiod on energy intake,thermogenesis, and reproduction in desert hamsters (Phodopus roborovskii)

Desert hamsters (Phodopus roborovskii) are the least known species in the genus Phodopus with respect to ecology and physiology, and deserve scientific attention, particularly because of their small body size. Here, the responses of energy metabolism and reproductive function to short photoperiods in desert hamsters were investigated. Male and female desert hamsters were acclimated to either long day (LD) (L:D 16:8 h) or short day (SD) photoperiods (L:D 8:16 h) for three months, and then the females were transferred back to an LD photoperiod for a further five months, while at the end of the SD acclimation the males were killed and measurements were taken for serum leptin as well as molecular markers for thermogenesis. We found that like the other two species from the genus Phodopus, the desert hamsters under SD decreased body mass, increased adaptive thermogenesis as indicated by elevated mitochondrial protein content and uncoupling protein‐1 content in brown adipose tissue, and suppressed reproduction compared to those under LD. However, different from the other two species, desert hamsters did not show any differences in energy intake or serum leptin concentration between LD and SD. These data suggest that different species from the same genus respond in different ways to the environmental signals, and the desert adapted species are not as sensitive to change in photoperiod as the other two species.     

Effects of hypothyroidism on gonadal function after transition of short day photoperiod in male golden hamsters (Mesocricetus auratus)

Thyroid hormones permit the annual reproductive transition of seasonal breeders. Although, precise function of thyroid hormones in seasonal breeding is not well understood. In the present study, we examined effects of hypothyroidism on the hypothalamus-pituitary-gonadal axis in adult male golden hamsters after transition of the short-day photoperiod (SD; 8 h light: 16 h dark) condition. We confirmed that hypothyroid, which had been induced by administration of thiouracil in drinking water for 4 weeks, did not have direct effects on testes in male hamsters under the long-day photoperiod. Plasma concentrations of free T3 and T4 decreased 15 weeks after transition of SD condition. Plasma concentrations of testosterone in the hypothyroid group decreased earlier than in the control group after the transition from LD to SD. In animals treated with testosterone after castration, plasma concentrations of LH in the hypothyroid group decreased earlier than in the control group after the transition of SD. On the other hand, pituitary response to GnRH for LH release did not change in castrated hamsters as a result of hypothyroidism. These results suggest that thyroid hormones act the hypothalamus and might be required to maintain GnRH secretion in male golden hamsters.     

Changes in the composition of milk and rumen contents in cows exposed to a high ambient temperature with controlled feeding

Summary Two pairs of Jersey cows were exposed to either 15 or 30°C air temperature; intake of dried grass was controlled, to be equal ai both temperatures. Exposure to 30°C caused increases in rectal temperature and in respiratory rates, and decreases in food intakes in both cows. Milk yield decreased by similar amounts at both temperatures, in association with the decreases in food intakes. The fat and protein content of milk decreased significantly at 30°C; the proportion of shorter chain fatty acids (C₆-C₁₄) in the milk fat also decreased at 30° C. The proportion of acetic acid in the rumen contents decreased significantly at 30°C, in association with a small decrease in pH. The results indicate that changes in the metabolism of cows occurred at 30°C, independently of changes in food intake.

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Resumen Dos pares de vacas Jersey fueron expuestas a una temperatura ambiente de 15° y 30°C. respectivamente; la ingestión de hierba seca se controló para que fuera igual en ambas temperaturas. La exposición a 30°C. aumentó la temperature rectal y la rata respiratoria condisminución de la ingestión de alimento en ambas vacas. La secreción láctea disminuyó en cantidades iguales en ambas temperaturas en asocio con una disminución similar en la ingestión de alimento. El contenido de grasa y proteína de la leche disminuyó significativamente a 30°C; la proporción de cadenas cortas de ácidos grasos (C₆-C₁₄) en la grasa de la leche también disminuyó a 30°C. La proporción de ácido acético en el contenido del rumen disminuyó significativamente a 30°C. en asocio con una peque?a disminución del PH. Los resultados indican que los cambios en el metabolismo de las vacas ocurrieron a 30°C. independientemente de los cambios en la ingestión de alimentos.

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Résumé Deux paires de vaches jersiaises ont été exposées à une température de 15° ou 30°. La même ration d'herbe sèche a été donnée aux animaux soumis aux deux températures. L'exposition à 30° a provoqué une augmentation de la température rectale et des taux respiratoires et une diminution de l'absorption alimentaire chez les deux vaches. La production de lait diminue de la même fa?on aux deux températures, en même temps que diminue également la ration alimentaire. La teneur en graisse et en protéine du lait baisse de fa?on sensible à 30°. La proportion d'acides gras à chaine courte (C₆-C₁₄) dans les graisses du lait décro?t aussi à 30°. La proportion d'acide acétique dans le contenu du rumen diminue de fa?on significative à 30° en même temps que le pH accuse une diminution légère. Les résultats indiquent que des changements dans le métabolisme des vaches se produisent à 30° indépendamment des modifications de la ration alimentaire.

     

Effects of supplemental L-carnitine in drinking water on performance and egg quality of laying hens exposed to a high ambient temperature

The present study was conducted to investigate effects of L-carnitine supplied with drinking water on performance and egg quality of laying hens under high environmental temperature. In the study, 47-week-old laying hens (Brown hisex) were divided into two groups (control and treatment) and fed with a standard layer diet. Treatment group was received 50 p.p.m L-carnitine with drinking water for an 8-week period. Throughout the study, 8 h hot (35-37 degrees C) and 16 h thermoneutral (20-22 degrees C) environmental temperature regime was employed daily. The results showed that L-carnitine supplementation affected some egg quality characteristics of layers under high environmental temperature. Relative albumen weight and height were increased (p < 0.05) by supplemental L-carnitine. Live weight gain, feed intake, egg mass, egg weight, yolk weight, shell weight, yolk index, egg-shape index, yolk colour score and shell thickness were not affected (p < 0.05) by L-carnitine. It is concluded that L-carnitine supplementation in laying hens could have potential to improve albumen quality under high environmental temperature.     

Behavioural and endocrinological changes in Syrian hamsters (Mesocricetus auratus) under domestication

This study aimed to quantify differences in response to stress between two strains of Syrian hamsters to evaluate the consequences of domestication in this species by measuring behavioural traits in the open-field, adrenal gland masses (ADR), and faecal and blood corticosterone concentrations (CC). We studied a laboratory (lab)- and a wild-derived population (wild). The lab hamsters were significant heavier than the wild hamsters. The lab males had the highest ADR, and it was independent of their high body mass (BM). The ADR of lab females and wild hamsters was linearly dependent of BM. The lab males had the highest faecal and blood CC, whereas the lab females had the lowest CC. In the open field, the lab hamsters began later to groom, groomed shorter, groomed less frequently, began later to rear, reared longer and reared less frequently. In the lab population, females reared more often and groomed longer than males. The sex differences in the behaviours of the lab population and the differences between the populations mirror the differences neither in the ADR nor in the CC. The founder effect and the breeding history of lab Syrian hamsters are discussed as causes of the differences between the studied populations.     

Lymphocytic choriomeningitis in laboratory personnel exposed to hamsters inadvertently infected with LCM virus

Seven of 27 students and staff oa a university laboratory became ill with lymphocytic choriomeningitis (LCM) following exposure over an 18-month period to hamsters implanted with tumors. The clinical symptoms were compatible with LCM infection and all the patients' sera had fluorescent antibody to LCM virus; 5 of them also had complement-fixing (CF) antibodies. Complement-fixing antibodies were found in 9 of 9 hamsters with tumors and 16 of 31 without tumors (excluding 6 hamsters with anticomplementary sera) and in 8 of 14 rabbits, but in none of 49 rats. Lymphocytic choriomeningitis virus was isolated from 4 pools of liver and spleen, 2 each from hamsters with and without tumors, and from a frozen stored sample of the tumor cells. Interlaboratory transmission may have occurred via infected tumor cells. Control was achieved by destroying all animals in the project room as well as all hamsters in the building. The possibility that many tumor cell lines carried in hamsters may be infected with LCM virus has important implications for laboratory safety as well as for the validity of the research results obtained, inasmuch as the virus enhances the growth of some tumors and retards others.     

Gastritis and intestinal metaplasia in Syrian hamsters infected with Helicobacter aurati and two other microaerobes

Chronic gastritis and intestinal metaplasia associated with naturally occurring colonization by Helicobacter aurati and two other microaerobic species were observed in Syrian hamsters. Thirty-five hamsters, between 7 and 12 months of age, were evaluated from two research and three commercial facilities. Microaerobic bacteria were cultured from the hamster stomachs. These bacteria included H. aurati, a fusiform, urease-positive species; a second novel helical, urease-negative Helicobacter sp.; as well as a smaller, urease-negative Campylobacter sp. Southern blot analysis detected Helicobacter spp. DNA in the gastric tissues of all 35 hamsters; 15 hamsters also had Campylobacter sp. DNA in their gastric tissues. When examined by light microscopy, argyrophilic bacteria consistent with H. aurati or the second Helicobacter sp. were present in antral sections of 12 out of the 15 hamsters where bacteria were seen, while 9 out of the 15 hamsters had bacteria resembling the Campylobacter sp. The presence of Helicobacter spp. but not the presence of Campylobacter sp. was significantly correlated to gastritis severity (P < 0.0001 for Helicobacter spp., P = 0.6025 for Campylobacter sp.) and intestinal metaplasia, as measured by numbers of goblet cells (P = 0.0239 for Helicobacter spp., P = 0.5525 for Campylobacter sp.). Severely affected hamsters also had Giardia sp. within their metaplastic gastric pits. Hamsters with naturally occurring helicobacter-associated gastritis provide a model for studying the development of intestinal metaplasia and gastric giardiasis in H. pylori-infected humans.     

The arrangement of the coronary artery trunks is subject to inheritance factors: A study in Syrian hamsters

The concept that anatomical variations in the coronary artery tree might be influenced by genes is relatively old. However, empirical evidence on the effect of genotype on the coronary morphology is still scarce. In the Syrian hamster, there is a septal coronary artery which arises from the left or from the right coronary artery and supplies most of the interventricular septum. The aim was to decide whether the anatomical origin of the septal artery is subject to inheritance factors. Overall, 483 internal casts of the heart and coronary arteries were examined. All the hamsters included in this study had normal coronary arteries. The results of 74 crosses were compared statistically to seek for any significant difference between the phenotypes of the offspring and the phenotypes of the parents. The left septal artery was over‐represented in the offspring of crosses between parents having both a left septal artery (p < .01), while the right septal artery was over‐represented in the offspring of crosses between parents, one with a right and the other with a left septal artery (p < .001), and, more markedly, in the offspring of crosses between parents both with a right septal artery (p < .001). These results are the first to reveal that the coronary artery pattern is influenced by genetic factors, at least in its proximal portion with regard to the aorta.     

Influences of wet feeding and supplementation with ascorbic acid on performance and carcass composition of broiler chicks exposed to a high ambient temperature.

In two experiments was investigated whether feeding with an air-dry feed mixed with different amounts of water and/or supplemental ascorbic acid affect performance and carcass compositions of broilers exposed to a high ambient temperature (35 to 37 degrees C for 8 h/d and thermoneutral for 16 h/d). In the first trial, 64 one-week-old male broiler chicks were fed ad libitum in four dietary treatment groups for a 6-week period. Experimental mash diets were prepared by mixing a maize-soybean based standard broiler starter or finisher with tap water in the ratios of 0.0:1.0, 0.5:1.0, 1.0:1.0 and 1.5:1.0 (water:air-dry feed, w/w). More water in the diet increased BWG, DMI, abdominal fat and carcass weight, carcass CP, crude fat, but it deteriorated DM conversion efficiency. In the second experiment, 64 one-week-old male broiler chicks were given air-dry or wet (water:feed, 1.5:1) starter or finisher diets without or with ascorbic acid supplementation (0 and 250 mg/kg air-dry feed, resp.) ad libitum for a 6-week period. Ascorbic acid supplementation increased BWG, carcass weight and carcass CP significantly, while reducing carcass crude fat content. However, feeding broilers with a diet mixed with water in a ratio of 1.5:1.0 increased BWG, DMI, carcass weight and carcass lipid markedly, but deteriorated DM conversion efficiency. There was also a significant interaction between ascorbic acid and wet feeding, whereby ascorbic acid supplementation induced a significant reduction in carcass lipid contents of broilers fed on air-dry diets but not on wet diets. It is concluded that wet feeding, especially an addition of 150% water to produce a porridge like consistency, improved growth performance by increasing fat, ash and protein deposition in the body, while reducing DM conversion efficiency. It is also concluded that under heat stress supplemental ascorbic acid in air-dry diets stimulates broiler performance but not in wet diets.     

低温诱发肉鸡腹水综合征发生过程中肺血管重塑与肺动脉高压的关系

将160只15日龄雄性AA商品代肉鸡随机分为对照组((22±1.5)℃)和低温组((11±2)℃)。15~50日龄,每组每周随机取6只,以右心导管法直接测定肺动脉压(PAP),并取肺组织做石蜡切片进行Weigert-间苯二酚复红染色,分析肺血管重塑情况。50日龄时统计整个饲养过程中肉鸡腹水综合征(AS)发生率。结果显示,低温组肉鸡AS发生率(18.75%)极显著高于对照组(1.25%)(P<0.01);低温组肉鸡PAP从22日龄开始较对照组明显升高(P<0.01或P<0.05);20~50、50~100、100~200μm肺动脉结构分别从36、43、43日龄开始较对照组发生了明显的重塑(P<0.01或P<0.05)。结果表明,低温诱发肉鸡AS过程中出现了明显的PAP升高和肺血管重塑,且肺动脉高压(PH)促进了肺血管重塑,肺血管重塑加剧了PAP升高。     

Acclimation to high ambient temperature in Large White and Caribbean Creole growing pigs

The effect of breed [Creole (CR) vs. Large White (LW)] on performance and physiological responses during acclimation to high ambient temperature was studied in 2 experiments involving 24 (12/breed) growing pigs each. Pigs were exposed to 24 degrees C for 10 d (d -10 to -1) and thereafter to a constant temperature of 31 degrees C for 16 d (d 1 to d 16) in Exp. 1 and for 20 d (d 1 to d 20) in Exp. 2. For both experiments, the temperature change was achieved over 4 h on d 0. The first experiment began at 105 d of age, and the average BW of CR and LW pigs was 36.6 +/- 2.5 kg and 51.7 +/- 3.0 kg, respectively. The second experiment was designed to compare both breeds at a similar BW (about 52 kg on d 0). Pigs were individually housed and given ad libitum access to feed. At 24 degrees C, ADG was lower (P < 0.01) in CR than in LW (602 vs. 913 g/d and 605 vs. 862 g/d in Exp. 1 and 2, respectively), but the ADFI was not affected by breed (190 and 221 g x d(-1) x kg(-0.60) in Exp. 1 and 2, respectively). Short-term thermoregulatory responses during the 4-h transition from 24 to 31 degrees C (d 0) were analyzed according to a linear plateau model to determine the break point temperature, above which rectal temperature (RT), cutaneous temperature (CT), and respiratory rate (RR) began to change. The CT increased linearly with temperature increase (0.22 degrees C/ degrees C) and was less (P < 0.05) in CR than in LW (by -0.3 degrees C on average). In both experiments, the break point temperature for RT was not affected by breed (27.6 degrees C on average), whereas for RR it was greater (P < 0.05) in CR than in LW (27.5 vs. 25.5 degrees C, P < 0.01). On average, ADFI declined by about 50 g x d(-1) x kg(-0.60) from d -1 to d 1 (P < 0.01), and thereafter at 31 degrees C, it gradually increased (23 g x d(-1) x kg(-0.60); P < 0.05), suggesting an acclimation to high exposure. This response was not influenced by breed. After the day that marked the beginning of the acclimation response (i.e., the threshold day), RR, CT, and RT declined over the duration of exposure to 31 degrees C (P < 0.05) in both experiments. During this period, RT and CT were less in CR than in LW pigs (39.6 vs. 39.9 degrees C and 37.9 vs. 38.2 degrees C, respectively; P < 0.05), whereas RR was not affected by breed. The threshold day at which RT began to decline was less in CR than in LW pigs (0.18 vs. 1.17 d and 0.39 vs. 0.93 d in Exp. 1 and 2, respectively; P < 0.05). In conclusion, this study suggests that short- and long-term physiological reactions during heat acclimation differed when CR and LW pigs were compared at the same age or BW.     

Effect of photoperiod and temperature on prolactin secretion in ovariectomized gilts

Five ovariectomized (OVX) gilts were placed in each of two chambers at 20 C with a photoperiod of 12 h light and 12 h dark for 8 d (12L:12D). On d 1, blood samples were collected via jugular cannula every 30 min from 0830 to 1630. At 1630, 200 micrograms of thyrotropin releasing hormone (TRH) were injected iv and blood samples taken every 10 min for 1 h and every 30 min for the next 2 h. On d 2, samples were taken every 30 min from 0830 to 0930 and from 1530 to 1630. Temperature was changed to 10 C or 30 C on d 3. Samples were taken from 0830 to 1630 on d 3, 4 and 9. At 1630 on d 9, the TRH challenge was repeated. Mean basal serum concentrations of prolactin (PRL) were similar for all gilts and for all periods. However, serum PRL response (ng PRL X ml-1 X 150 min-1) to TRH increased (P less than .0001) after exposure to 30 C, while exposure to 10 C failed to alter PRL response. In Exp. 2, six ovariectomized gilts were assigned to each chamber. The protocol of Exp. 1 was followed through d 3, except temperature and photoperiod were changed to 10 C and 8L:16D or 30 C and 16L:8D. On d 34 the TRH challenge was repeated. Mean basal serum concentration of PRL was similar for all gilts and all periods. However, simultaneous increases in temperature and photoperiod increased (P less than .005) serum PRL response to TRH, whereas simultaneous decreases in temperature and photoperiod failed to alter PRL response to TRH.     

Colonic ulceration and increase of neutrophil elastase activity in the acetic acid-induced colitis model in Syrian hamsters

A novel colitis model using Syrian hamsters was developed. Colitis was induced by intracolonic administration of 1% acetic acid, and the ulcer area, tissue myeloperoxidase (MPO) activity, and luminal neutrophil elastase (NE) activity of the colon were determined at 1, 3, 8, 24 and 48 hr after colitis induction. The histopathological changes of the colon were also examined in this model. An increase of tissue MPO activity and NE activity was evident at 3 hr after induction of colitis, peaked at 24 hr, and decreased subsequently. The increase of luminal NE activity was well correlated with the colonic ulcer area. In histopathological examination, ulceration, erosion, crypt abscesses, neutrophil infiltration, hemorrhage, and edema were seen. The effects of prednisolone were examined to evaluate the adequacy of our colitis model. Syrian hamsters were treated orally with prednisolone at 18 and 1 hr before and at 6 hr after induction of colitis, and the ulcer area, tissue MPO activity, and luminal NE activity were evaluated at 24 hr after colitis induction. Prednisolone therapy had little effect on the tissue MPO activity. However, the NE activity of the prednisolone-treated group was significantly decreased. In addition, although prednisolone did not significantly decrease the ulcer area, a tendency toward decrease was noted. We conclude that this new model of experimental colitis in Syrian hamsters is useful for investigating the pathophysiology of colitis, especially useful for studying the relationship between colitis and NE activity.